Known electrical junction boxes of this type include, for example, the type disclosed in Japanese Patent Laid-Open No. 8-322127. The electrical junction box consists of a housing which houses a power distribution board composed of a plurality of bus bars disposed along insulating substrates, where electrical components such as relays to be connected to the power distribution board are arranged and mounted on the upper surface of the housing.
With the above configuration, however, the electrical components such as relays generate heat when conducting electricity. The heat emitted from adjacent electrical components does not dissipate sufficiently and may build up gradually. The heat buildup may cause problems such as deformation of parts and the like, and thus it is desirable to dissipate the heat out of the electrical junction box quickly.